High-sensitivity cathode-ray tube



July 3, 1962 H. M. o wREN HIGH-SENSITIVITY CATHODE-RAY TUBE Filed April16. 1959 JNVENToR. HAP/ffy wPf/v rroPA/iy Y 3,042,332V mon-sartsrrmrrcArHonr-RAY TUBE Harvey M. wren,

tronics, Inc., fornia Filled Apr. 16, 1959, Ser. No. 866,886

11 Claims. (Cl. 315-18) Livermore, Calif., assigner to Ab- Liverrnox'e,Calif., a corporation of Cali- The present invention relates in generalto an improvement in the sensitivity of cathode-ray tubes, and

more particularly to electrode means for a cathode-ray tube operating toadditionally deilect and accelerate an electron beam therein to the endof providing improved tube sensitivity and magnifica-tion whilepreserving the beam focus therein.

It is highlyv desirable in any application of cathoderay tubes toprovide a maximized beam deflection in the tube tothe end of providing asweep of extended length and also it is highly desirable to provide .amaximum screen brilliance. Although it is possible to attain in partthese objectives by conventional means such as increasing the normaltube deecting voltage or current yet such conventional approaches arelimited in that same generally impose undue requirements on auxiliarytube circuitry. Thus, for example, requisite voltage variations andpower delivery that would be necessary for such approaches wou-ld lbeexcessive sol as to preclude widespread usage thereof. Further, theadditional acceleration of cathode-ray tube beams imposes in itself aserious ditiiculty. Full beam acceleration to very high beam energyprior to beam deiiection has been found to be undesirable because ofdifficulties encountered in the deecting system, i.e., the problem ofachieving desired deection and control of the beam. `Post-deflectionacceleration, i.e., acceleration of the beam after deflection, Whileovercoming the above-noted diiiiculties raises other problems in thatimage distortion results. While postdeilection acceleration systems areknown and used, the tube resolution in such instances suifers thereby sothat systems of that type are inherently limited, at least in theirpresently knownform. Furthermore, conventional post-acceleration methodsare directed to preserving the deflected beam `direction so as to beapplicable only Vin connection With increasing beam energy withoutimprovement of tube sensitivity.

The present invention is directed to overcoming the above-noteddifculties encountered in the cathode-ray tube ant as well as to theprovision of other advantages in such art. It is contemplated Aby thepresent invention that there shall be provided within a cathode-ray tubeand following the deflection means thereof, auxiliary or secondary beamaccelerating electrodes which are so formed and disposed as to define,yby appropriate potentials impressed therebetween, the electron beamaccelerating and deflecting fields. Contrary to conventionalpost-deflection acceleration systems previously employed in Ithecathode-ray tube art, the present invention operates to additionallyaccelerate an electron beam and to magnify the original controlleddeilection thereof without introducing image distortion. This is hereinaccomplished by the provision of spherical electric yfields wherein beamacceleration is accomplished in the direction of deiiection rather thanparallel to the tube axis. In this manner the present invention iscapable not only of further accelerating cathode-ray tube beams but alsoof further deflecting same in a uniform manner so that the resultantbeamV impinging upon the cathode-ray tube Screen is additionallyradially deflected to thereby expand or magnify the trace appearinguponV the screen and at the same time lto further energize the beam soas to intensify the magnified trace on the screen. The

the end of the chamber and an 3,642,832 Patented July 3., 1962 fire 2foregoing is accomplished without in any way detracting from the traceresolution or in any way distorting the image or display.

In accordance' with the foregoing it is an object of the presentinvention to provide the cathode-ray tube Vof improved sensitivity.

It is another object of the present invention to provide a cathode-raytube with secondary or auxiliary beam deflection means for maximizingmagnification of ythe tube display. f

It is a further object of the present invention to Aprovide acathode-ray tube improvement including means producing post-deectionbeam acceleration without image distortion. Y

It is yet another object of the present invention to provide an improvedcathode-ray tube including means further accelerating the electron beamtherein in a deected direction for increasing beam energy while at thesame time magnifying beam deiiection.

Various other advantages and possible objects of theV present inventionwill become apparent to those skilled in the art from the followingdescription and drawing wherein there are illustrated several preferredembodiments of the present invention. Although only particular preferredembodiments of this invention are herein illustrated and described, itis not intended to limit the invention -by the terms thereof but insteadreference is made to the appended claims for a precise delineation ofthe true scope of the present invention.

The invention is illustrated in the accompanying drawing, wherein:

FIG. 1 is a schematic illustration of a cathode-ray tube including theimproved accelerating and dellecting means of the present invention;

FIG. 2 is a schematic illustration of a portion of a cathode-ray tubeincluding an alternative embodiment of the present invention;

FIG. 3 is a schematic illustration of a portion of a cathode-ray tubeincluding a further embodiment of the present invention; and

FIG. 4 is a schematic illustration of a portion of a cathode-ray tubeincluding yet another embodiment of the present invention. i

Considering now the present invention in some detail as regards thepreferred embodiments thereof illustrated, and referring to FIG. 1 ofthe drawing, there Will be seen to be illustrated in schematic formtherein a cathoderay tube 11 including an evacuated envelope 12. Inconformity with conventional cathode-ray tube practices, the envelope 12defines an expanded chamber 13 at one end thereof with acathodoluminescent screen 14 disposed at elongated neck or tube 16extending from this screen 14 to house at the opposite end of the neckan electron beam source17. This electron beam source 17, uponappropriate and conventional energization, not shown, is adapted toproduce an electron beam and to direct same along an axis 20 of thecathode-ray tube which intersects the tube screen 14 at the centerthereof. Along the tube axis from the electron beam source 17 there isprovided a primary electron lens 18 Which may, as illustrated, include aplurality of elements spaced along the tube axis and through which theelectron beam is adapted vto pass for accelerating and focusing same.Following the primary lens system 18 there are provided deection means19 spaced along the tube axis and including horizontal and verticaldeiiection means such as the pairs of plates illustrated. It Will beappreciated of course that either electrostatic or electromagneticdeflection means may be employed in conventional manner in the cathodetube modified by the present invention and also that conventionalenergization of the tube elements is intended. An electron beam 21emitted from the beam source 17 and passing axially through the primaryelectron lens 18, is radially defiected in passing through thedeflecting means 19 and such deflection is normally accomplished in sucha manner as to impart desired intelligence to the beam, such as, forexample, by the application in an electrostatic deflecting system ofsuitably modulated defiecting potentials. The beam 21, upon emergencefrom the deflecting means and passage through the chamber 13, isdeflected to radially separate, as regards consecutive beam portion, tothereby impinge upon the screen 14 at successive spaced points toprovide a trace thereon. Considering a single beam portion, forsimplicity of explanation, there is indicated in FIG. 1 by the dottedline 22 the path followed by such a beam portion receiving a particularradial deflection in passage through the deflecting means 19 in aconventional cathode-ray tube. As noted above, conventional cathode-raytubes, as described to this point, are limited in the maximum beamenergy that may be provided, for inasmuch as beam accelerat-ion isnormally accomplished' in the primary electron lens or source, suchacceleration is prior to beam deflection and consequently with too higha beam energy or velocity as a result of excessive beam acceleration thedeflecting means become unable to provide the desired beam deflection.This results from the limited time in which the electron beam issubjected to the deflecting forces of the deflection means and suchdeflection time will be seen to be a direct function of the beamvelocity. As regards sensitivity, conventional cathoderay tubes arelimited by the fact that large beam deflections require large spacingbetween deiecting plates so that the defiected beam will not strike sameand with increased spacing between deflecting plates, there results alesser effect upon the beam by any particular potential applied to theplates. The present invention provides close spacing of the deflectingplates so that only very small deflecting potentials are required.

The present invention provides means for additionally acceleratingelectron beams in a cathode-ray tube after controlled deflection thereofand for magnifying the defiecton without distortion of the resultantdisplay. To this end there is herein provided, as shown in FlG. l, afirst electrode 26 disposed symmetrically about the beam axis adjacentthe deflecting means 19 and toward the screen 14 therefrom. This firstelectrode 26 defines a semi-spherical surface and may to this endinclude a spherical portion 27 facing the screen 14 and including ordefining a beam-transparent section of the electrode. This transparentportion of the electrode 26 is disposed immediately about the tube axisso as to admit of passage of the beam through the electrode. As shown inFIG. 1, the electrode 26 is formed as a hollow cylinder having aspherical end directed toward the screen 14 with an opening 28 throughsuch end for the passage of an electron beam therethrough. Thisspherical electrode portion 27 is disposed with the center 29 of thespherical surface located upon the tube axis. Displaced axially of thetube from the first electrode 26 is a further electrode 31. This furtherelectrode 31 also defines a spherical surface as by a semi-spherical endportion 32 formed on a radius of curvature substantially greater thanthat of the spherical portion 27 of the electrode 26, but however havingthe same center 29. The electrode 31, which is preferably radiallydisplaced from the tube axis so as to be disposed adjacent the sides ofthe envelope 12, is also provided with a central beam transparentportion which, as is illustrated in FIG. 1, comprises a large opening3'3 which may in fact approach the size of the tube screen 14. inasmuchas the electron beam is radially deflected in passage through theelectrodes of the present invention, a substantial beam opening isrequired in the electrode 31 in order that the beam 21 will not impingeupon the electrode. Intermediate the electrodes 26 and 31 there may beprovided a further electrode 36 formed with a spherical surface 37having the same center 29 as the spherical surfaces of the otherelectrodes and having a radius of curvature intermediate of the radiusof curvature of the electrode 36 and electrode 31. Similar to theabove-described electrodes 26 and 31, the intermediate electrode 37 isprovided with a central beam.v transparent portion 38 disposedsymmetrically about the tube axis and providing an unobstructed passagefor the beam 21 through the electrode. In the illustrated ernbodiment,the intermediate electrode 36 is disposed equidistant between theelectrodes 26 and '31 although other disposition thereof is possible.Suitable physical mounting of the electrodes within the envelope may beaccomplished in accordance with conventional tube practice and is thusnot illustrated. Also the electrode 31 may be formed upon the tubeenvelope.

Electron beam acceleration and deflection is accomplished by theabove-described electrodes through the application of suitablepotentials to these electrodes for forming defiecting and acceleratingelectric fields in the beam path. Electrical potentials are appliedbetween the electrodes in such a manner as to maintain the firstelectrode 26 at a relatively negative potential with respect to theelectrode 31 and further to maintain the intermedia-te electrode 36 atan intermediate potential of a value dependent upon the physicallocation of same between the other two electrodes 26 and 31. Electricalconnection is made, as by means of conductors 41, 42 and 43, from theelectrodes 26, 36 and 31, respectively, into connection at appropriatepoints upon such as a voltage dividing resistor 44 connected across apower supply, illustrated as a battery 46.

The intermediate electrode 36 is maintained at an appropriate potentialto further establish the spherical deflecting and accelerating field. Asillustrated, the electrode 36 is maintained at a potential about 0.7 ofthe total voltage between electrodes 26 aud 31, as by con-g nection tothe center of a logarithmic resistor 44. Any desired number ofelectrodes may be employed to establish the desired spherical fieldconfiguration and appropriate potentials applied thereto for thispurpose, however, somewhat different potentials may also be employed inorder to distort the field to produce certain desired results such ascompensation for some other cause` of distortion or suitable directionof the beam onto a planar screen.

By the foregoing electrical connection of the electrodes 26, 31 and 36,there is established an electric field intermediate the `deflectingmeans 19 Iand screen 14 of the cathode-ray tube wherein the field linesare normally spherical -about the tube axis. Thus, between theelectrodes 26 and 31 there is established an electric field having linesof equal potential which lie upon spheres having the electrode center 29as the center thereof and, 'in effect, radiating outward therefrom. Theintermediate electrode 36 operates only to further define this field,particularly wherein the physical separation of the electrodes 26 and 31is substantial. It will be seen from a consideration of the electricfield established by the electrodes of the present invention, that thereis provided thereby a potential gradient `axially of the tube andradially thereof. With the electrode 31 closest to the tube screen 14maintained at a relatively positive potential with respect to theelectrode 26 disposed adjacent to tube deflecting `means 19, thispotential gradient operates to urge electrons within the field axiallyof the tube toward the screen 14 and radially of the tube outward of theaxis thereof. Consequently, an electron beam fdefiected by thedeflecting means 19 and passing through the electrode 26 enters aspherical electric field of substantial extent wherein the potentialgradient is of proper polarity to urge electrons radially outward oflche tube and 4also to urge electrons toward the screen 14. With ythefield established by the electrodes of the present invention, adeflected electron beam is thereby accelerated toward the screen 14-While at `the same time being deflected radially outward of the tubeaxis. `In eEeot, electron acceleration occurs in the direction ofdeflection so that consequently no distortion of the beam displayresults, -as would be the case with electric fields established normalto the tube axis and extending perpendicularly therefrom. In addition tothe general case of exactly spherical fields, there may herein bereadily introduced such variations in the elds as are necessary tocompensate for distortions that otherwise result in the display fromother causes. This is herein accomplished by variations in the shapeofthe intermediate electrodes or in the potentials applied thereto.

A modification of the present invention is illustrated in part in FIG, 2wherein there is shown the electrodes 26, 3-1 and'36 of the presentinvention substantially as illustrated and employed in FIG. l,`described above.v The modification herein illustrated is that ofproviding a continuation of each of the electrodes into -a completesphere o-r semi-spherical surface about the tube axis. Such electrodecontinuation is herein made in the form of electronic grids 51, `52 and53, enclosing the electrode openings 2S, 38 and 33, respectively. Theseelectronic grids are disposed, as above stated, upon a spherical surfacewhich is, in the case of each electrode, a continuation of the electrodecurvature. Additionally, these grids VSi, 52 and 53 are formed in aconventional manner as a very high permeancel structure, as for example,of wire mesh. Stated otherwise, each of the grids has a highItransmissivity or transparency for electrons and are thus formed with amaximum area of openings therein and a minimum area of grid wires orelements. With the grids having a high transmission factor for theelectron beam only a very small proportion of the beam is interceptedthereby so that problems of grid heating or beam attenuation orminimized. The function of the grid structures illustrated in FlG. 2 isto Afurther delineate the electric field established by the electrodesof the present invention. 'Ilhere is illustrated in FIG. 2 by the lines54 a representation of equipotential lines resulting from theabove-noted potentials applied to the grids. It will be seen that theselines 54 have the same radius of curvature as the electrodes and -aseach other inasmuch as each lies on circles having the common center 29of the electrodes. Also illustrated in FG. 2. are lines of force of theelectric field established by the electrodes and such are thereby shownas dashed lines 56 which will be seen to emanate uniformly from thefirst electrode 26 radially outward of the tube axis and directed towardthe tube screen with the focal point of the lines being the center ofcurvature 29 of the electrodes. It will be appreciated that electronsentering'the field established between the `electrodes 26 and 3l of thepresent invention will tend to follow the lines of force 56 illustratedin FlG. 2 and that also electrons following such lines of force Iwill beaccelerated along same inasmuch as the positive terminal ofthe field isdisposed adjacent the screen 14 of the tube. Consequently it is clearfrom ia study of PEG. 2 that an electron beam passing through the rstelectrode 26 and entering the electric field established by theelectrodes will in fact be radially deflected While at the same timebeing accelerated in the direction that the beam is traveling so thatthe electrodes thereby operate not only to further energize the beam butalso `to radially deflect same -outwardly of the tube axis. Theacceleration imparted to the beam by the field established with theseelectrodes is not parallel -to the tube axis, yand therefore does notoperate to distort the display so that no reduced resolution accompaniesthe intensication.

A further embodiment of the present invention is illustrated in BIG. 3of the drawing wherein a relatively inverted electrode system isillustrated. In this embodi- 6 ment of the invention there is provided afirst semispherical electrode 6l having the center of curvature 62thereof disposed upon the beam axis 20, but in this instance oriented toprovide the convex electrode surface in facing relation to thecathode-ray tube deilecting means i9. This electrode 6l is disposedadjacent the deflecting means 19 of the cathode-ray tube and is providedwith a central opening or electron beam transparent portion 63, aboutthe tube `axis Ztl of suicient diameter to accommodate the deflectedbeam 21 passing therethrough. An additional electrode 64 is provided asa semi-spherical element'having the same center 62 as the electrode 61and having a much smaller radius of curvature than that ofthe priorelectrode 61. This second electrode 64 is disposed intermediate thefirst electrode 61 yand the tube screen 2,4 with the convex side thereoffacing the concave side of the electrode 61 and has a -minute opening 66therein about the tube axis 20 for the passage of an electron beamtherethrough. As an additional portion `of this second electrode 64there is preferably provided a diverging funnel or horn-shaped portion67 directed toward the screen 14 and flaring outwardly toward same.

.As in the above described embodiments the spherical electrodes of thepresent embodiment are adapted .to establish therebetween a sphericalelectric field for deflecting and accelerating an electron beam enteringsame. To this end the electrodes are connected to a suitable source ofpotential, herein illustrated as a battery 68, maintaining the firstelectrode 6l at a relatively negative potential with respect to thesecond electrode 64.

It will be appreciated from a consideration of the electrostatic fieldconfiguration established by the relative potentials of the electrodes61 and 64 that an electron beam 21 entering the electrode field regionof the embodiment illustrated in FIG. 3 will undergo a deflection whichwill, in fact, reverse the beam dellection radially of the tube. Linesof force of the deflecting electric field will be seen to convergetoward the screen 14 rather than oppositely, as in the above describedembodiments of the invention, and thus `the radial potential gradientacting upon `an electron 4beam entering the held urges the beam towardthe axis of the tube so that the beam is in fact redirected. The beamdeflection produced by the spherical accelerating and dellecting fieldsof this embodiment of the invention is such as to cause the beam tocross the tube axis and the 'resultant radial beam deflection isproportional to the original deflection but in excess thereof. It willbe seen further that with the second spherical electrode 64 having arelatively small radius of curvature and also a relatively small beamopening 66 therein, that the electron beam is generally constrained tofollow lines of force of the electric field and will be in fact focusedthrough the electrode aperture 66 to pass generally through the centerof curvature 62 of the electrodes and thence onward in a relativelyfield-free region within the funnel or horn 67 into impingement upon thescreen 14. In this instance the second electrode 64 and funnel or horn67 thereof may be electrically connected to the screen'14 Vso that thereis in fact established an electric field free region through which thebeam passes after entering the second electrode 64. Inrthe abovedescribed embodiments the electrode adjacent the screen of thecathoderay tube may also be electrically connected thereto. Here againin lthe embodiment of the present invention illustrated in FIG. 3 of thedrawing, an electron beam 21 entering the'electric iield establishedbetween the electrodes of the present invention will experience anacceleration toward the screen 14 along the deflected path of the beamwhile at the same time experiencing a radial potential gradientoper-ating to further radially deflect the beam. Thus in this embodimentthe same result pertains in that following conventional beam deflectionof :the cathode-ray tube there is established a spherical electric fieldin the beam path which operates to further accelerate and deflect theelectron beam whereby such beam impinges upon the cathode-ray tubescreen at an increased energy and with an increased radial deflection.

The improved electron beam accelerating and deflecting system of thepresent invention is also adapted to various other applications as, forexample, the one illustrated in FIG. 4 of the drawing. Therein there isshown an electrode system including first, second and third electrodes71, 72 and 73 disposed in the named order between cathode-ray tubedeflecting means 19 and screen 14. As in the embodiments of FGS. 1 and2, the electrodes 7l, 72 and 73 are herein formed `as sphericalsurfaces, or at least semi-spherical surfaces, with a common centerdisposed on the tube axis and with the electrodes disposed symmetricallyabout the axis. The electrodes are provided with electron beam openingstherethrough of progressively increasing size toward the cathode-raytube screen in order to afford adequate passageway for an electron beamtraversing the tube to the screen thereof.

As a departure from the above teaching, there is provided in thisembodiment a thin sheet or film 74 across the opening in the firstelectrode 71 disposed adjacent the deflecting means 19. This iilm 74lies upon the spherical surface of the electrode to define with theelectrode the semi-sphere thereof. Additionally, this film 7e is formedof a material that is a good emitter of secondary electrons uponbombardment by primary electrons. More particularly the film 74 isadapted to produce from the convex side thereof a plurality of electronsfor each electron impinging the concave side of the film with suchemission occurring directly through the film from the point ofimpingernent of the primary electron. t will thus be seen that adeflected primary electron beam Z1 of the cathode-ray tube strikes thefilm 74 upon the concave side thereof to produce thereby an electronbeam 76 formed of secondarily emitted electrons from the convex side ofthe film 74, which secondary electrons are then further-accelerated by aspherical field established by the electrodes 71, 72 and 73. As notedabove, electrons are secondarily emitted from the convex side of thefilm 74 directly opposite the point of impingement of a primary electronon the concave side thereof so that in effect the secondary electronbeam 76 forms `a continuation of the primary beam but is composed of amuch greater number of electrons. Suitable electrical connections fromthe electrodes 71, 72 and 73 to appropriate points on a voltage dividingresistor 77 connected across a power supply, illustrated yas a battery78, serve to establlish a spherical electric field symmetrically aboutthe tube axis 20 in the same manner as described above in relation toFIG. 1. It will be seen that the spherical magnetic field established bythe electrodes 71, 72 and 73 of FIG. 4 operate in the same manner asdescribed above in connection with PIG. 1 to provide an additionalelectron beam acceleration to thereby materially increase the beamenergy and further to additionally radially defleet the beam inproportion to the amount of the original ydeflection accomplished in thedeflecting means 19 of the cathode-ray tube.

A further and material advantage of the embodiment of FIG. 4 is that ofproviding a substantial increase in the beam current by the utilizationof a secondary emitter' in the beam path. It is herein contemplated thatthe primary electron beam of the cathode-ray tube need not be of a highcurrent value, for the multiplication afforded by the secondary emitter74 is sumcient to provide a resultant or secondary beam 76 having acurrent density greatly in excess of those available from conventionalcathode-ray tubes.

An improved cathode-ray tube constructed in accordance with theprinciples of the present invention has, during operation and test,proven to have a sensitivity some ten times that of conventionalcathode-ray tubes. A suitable ratio of radii of first and lastelectrodes has been found to lbe 5:1. Additionally, an advantage of thepresent invention lies in the fact that deflection sensitivity may bemade materially higher even with a high final beam energy as thedeflection is largely independent of the final potential. It is also tobe noted in connection with the present invention that additionalfocusing of the electron beam may be provided by appropriate control ofthe relative potential between the electrode system and the electron gunassembly, including the `abovedefined electron beam source and primaryelectron lens.

What is claimed is:

1. A high-sensitive cathode-ray tube comprising an electron beam source,deilecting means for controllably deilecting an electron beam therefrom,a screen for intercepting said beam, and a plurality of electrodesdisposed along said beam path intermediate said deflecting means andsaid screen and establishing substantially semi-spherical electricfields symmetrically about the tube axis with lines of force radiatingfrom a point which is disposed on said tube axis and is displaced fromsaid deflection means for further deflecting said beam radially outwardof the tube axis to spread same upon said screen.

2. in a cathode-ray tube having means establishing an electron beamalong an axis thereof and means controllably deilecting the beam fromsaid axis to impinge at controllable points on a tube screen displacedaxially of the tube: the improvement comprising at least two electrodesspaced along the tube axis intermediate the deflecting means and screen,said electrodes being disposed symmetrically about the tube axis andeach defining thereby, including projections thereof, a semi-sphericalsurface with each having a common center of curvature displaced 'alongthe tube axis from the beam deflection means of the tube; and meansapplying a potential difference between said electrodes to maintain theone nearest said screen positive with respect to the other forestablishing beam eflecting and accelerating fields.

3. Electron beam deilecting and accelerating means for a deviceproducing an electron beam and controllably deiiecting same to directthe beam upon a screen displaced axially of the device from the point ofbeam deflection, and comprising at least two electrodes havingconcentric semi-spherical shapes and each disposed symmetrically aboutthe axis of said device, said electrodes each having a portion about theaxis of said device which is transparent to said electron beam, andmeans maintaining upon said electrodes a potential of decreasingpositive polarity from the electrode adjacent said screen to the oneadjacent the beam deflection for establishing spherical electric fieldsin the path of said beam, said fields having coincident centers ofcurvature displaced along the tube axis toward said screen from saidcontrollable beam deflection to further deflect said beam radiallyoutward of the device and to accelerate same in such deflected directionwhereby the beam impinges upon said screen at radially displacedpositions without beam defocusing.

4. Means claimed in claim 3 further defined by said electrodescomprising a pair of concentric segments of spheres of different radiusdisposed symmetrically about said axis with the center of curvaturedisposed thereon and the one with the larger radius disposed adjacentsaid screen with the convex side thereof facing said screen.

5. Means 'claimed in claim 3 further defined by said electrodes eachhaving a central grid portion of high transparency for electrons andeach of said portions being disposed symmetrically about the axis ofsaid device.

6. An improved cathode-ray tube comprising an electron beam sourceprojecting an electron beam along an axial path, deflecting meansadapted for controlled energization to radially deflect an electron beamdirected therethrough, a screen displaced from said deflecting meansalong the beam axis and disposed to intercept said beam, a firstelectrode having a centrally apertured spherical portion disposedsymmetrically about said beam axis adjacent portions therein saiddeflecting means, a second electrode disposed between said firstelectrode and said screen and having a centrally apertured sphericalportion disposed symmetrically about said beam axis concentrically withthe spherical portion of said first electrode, the spherical portions ofsaid electrodes having the centers of curvature thereof disposed on thetube axis toward said screen from said deflectingy means, and meansmaintaining said second electrode at a positive potential with respectto said first electrode for establishing a radially diverging electronaccelerating field whereby an electron beam traversing same isaccelerated and deflected radially outward of the beam axis into out-Wardly displaced impingement upon said screen.

v 7. Beam deflection and acceleration means for a cathode-ray tubeincluding a beam source directing a beam along an axis through the beamdeflection means toward a screen, and comprising a pair of concentricsemi-spherical electrodes spaced along said axis between said deflectingmeans and screen with each having beam transparent about said axis andadapted to have a potential impressed therebetween with the one nearestsaid screen maintained at a relatively positive potential with respectto the other for establishing beam accelerating and deecting fieldsdiverging from a point on said axis displaced from said deflecting meanstoward said screen and operating substantially uniformly upon anelectron beam passing at any deflection therethrough.

8. Beam deflection and acceleratoin means as defined in claim 7, furtherdefined by the first of said electrodes having a Vgreater radius ofcurvature than the second and disposed on the opposite side of thesecond electrode from said screen, said iirst electrode having a largebeam transl 10 parency for electron beams to define spherical electricfields shaped about the axis of the tube.

10. Beam deflecting and accelerating means for a cathode-ray tube havingan electron beam source directing a beam axially of the tube toward atube screen through deliecting means operable to controllably radiallydeiiect the beam, and comprising a plurality of electrodes spaced alongthe tube axis between said defiecting means and said screen with each ofsaid electrodes defining a semi-spherical surface disposed symmetricallyabout the tube axis, said semi-spherical electrode surfaces beingconcentric and parallel and having coincident centers of curvaturedisplaced along /the tube axis from said defiecting means, and saidelectrodes being adapted to have impressed therebetween electricalpotentials of increasingly positive polarity toward said screen toestablish uniformly diverging electron beam accelerating fields forfocusing said beam at radially displaced points on the screen.

11. Beam deflecting and accelerating means as claimed in claim 10,further defined by one of said electrodes disposed closest to saiddeflecting means having a portion of parent portion therein, and saidsecond electrode having a minute beam transparent portion thereinthrough which the beam is focused by fields established 1between theelectrodes. Y

9. Beam defiecting and accelerating means as claimed in claim 7 furtherdelined by the beam transparent portion of said electrodes comprisingelectrical grids of high transthe spherical surface defined therebyintercepting the tube axis, said portion being formed of a sheet ofsecondarily emissive material producing on the side facing said screen aplurality of electrons for each electron of said beam striking theopposite side at a point directly through the sheet therefrom.

References Cited in the le of this patent UNITED STATES PATENTS2,114,572 Ressler Apr. 19, 1938 2,315,367 Epstein Mar. 30, 19432,827,592 Bramley Mar. 18, 1958 FOREIGN PATENTS 802,715 France June 13,1936 473,675 Great Britain Oct. 18, 1937 553,466 Great Britain May 24,1943 109,216 Sweden Dec. 7, 1943

